Matrix for sound-records



F. G. MAYER.

MATRIX FOR SOUND RECORDS. APPLIQATION FILED JULY 2. me;

Pdtented J an. 13, 1920.

Ira Vania) v v by 7 La Af0772y3 UNITED STATES PATENT OFFICE.

FRED G. MAYER, OF RICHMOND, INDIANA, AIGNOB T0 THIi. STARR PIANOCOMPANY, OF RICHMOND, INDIANA, A CORPORATION OF INDIANA.

MATRIX FOR SOUND-RECORDS.

To all whom it may concern:

Be it known that I, FRED G. MAYER, "a citizen of the/United States,residing at Richmond, in the county of WVayne and State of Indiana, haveinvented certain new and useful Improvements in Matrices forSound-Records, of which the following is a full, clear, and exactdescription.

In the manufacture of sound records for phonographs it is customary toelectrotype a copper or other metal matrix sheet, to sweat this onto asuitable backing, and to use the compound structure as a matrix for theplastic record. It is usual to grind this matrix backing by hand on arotary grindstone for the purpose of getting a surface for solderin thebacking and matrix shell together, WlllCll operation has a tendency tomake the backing thinner in the center portion. Furthermore, theelectroplated shell which is soldered to the backing is usually thinnerat the center,by reason of the copper metal depositing more heavil onthe edges, in the course of electroplating, than in the center portion,this latter action being the chief cause of the decreased thickness inthe center of the complete matrix.

From this it results that the record disks produced by the usual dieproces have central portions ofslightly greater thickness than theremaining portions, but however slight this may be it is a source of thegreatest trouble, inconvenience and expense, for when such records arestacked or packed, the slightest elevation or increase ofthickness atthe center renders the disks liable to be cracked whenany weight orpressure is put upon them.

- It is not exceptional to make records with depressed centers. This isusually done by a circular elevation secured to other matrices orotherwise, such depressions having more or less abrupt edges or walls,which also causes the labels to break if they are larger than thiscenter depression, but I find that there are other practicableobjections to this plan, and in an effort to improve and to provide amore simple and economical method of producing them I have. devised theplan which forms the subject-matter of my present application.

Specification of Letters Patent.

Patented Jan. 13, 1920.

' Application filed J uly 2, 1919. Serial No. 308,197. I

According to my invention, I produce the matrlx sheets 1n. the usualmanner, and sweat them on to the usual backing, but whether they bethinner at the center or not is of no special moment,,for I employ athin disk of be slightly higher at the central portion than elsew mm,the elevation being so gradual as to be practically unnoticeable. Itwill, however, be ample to producerecords which arethinner at the centerand not liable to breakage, as they would be, were they the leastparticle thicker at such point. t

This improvement is illustrated in the accompanying drawingi Figure 1 isa plan view of one-half of a matrix sheet, on its backing, and showingthe thin metal disk when under the same.

Fig. 2 is a cross-sectional view of the completed matrix. A is thematrix sheet, B is the back, an C is the thin copper disk soldered orsecured to the backing and the sheet around the central opening D. Thelatter may be reinforced with the usual eyelet, and the disk is thinnedoff or tapered at its edge as shown,

This matrix or means for making phono- FRED G. MAYER.

